Vehicle fast torque coordination

ABSTRACT

Rapidly changing torque demand is coordinated in an automotive vehicle having an engine and at least one motor. An engine base torque level indicating slowly changing torque produced by the engine is received. A motor torque is determined as a difference between a fast desired torque and the engine base torque level. An engine fast torque is determined as a difference between the request for fast desired torque and the motor torque. The motor torque is determined as a motor torque request and the engine fast torque is determined as an engine torque request.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to the control of torque in a vehicle.More particularly, the present invention relates to coordinating rapidlychanging torque demand in an automotive vehicle with a plurality oftorque producing elements.

2. Background Art

Vehicle control systems accept requests from the vehicle driver andvarious vehicle components as well as output from vehicle parametersensors. Vehicle controllers use these inputs to generate controlsignals for vehicle equipment. Conventional control systems applied toautomotive vehicle applications were used to improve engine operation inorder to reduce vehicle emissions. Since these early attempts, enginecontrols have continued to grow in complexity as opportunities areidentified to make further improvements in performance, emissions, fueleconomy, and the like. Since the engine controller is still typicallythe most complex control system on the vehicle, it remains the primaryrepository for most new vehicle control algorithms as they aredeveloped. This has resulted in two problems with conventional enginecontrollers.

First, several control features that reside in the engine controller arenot engine specific. For example driver demand algorithms, whichdetermine the desired traction torque or force required by the driver,are often resident in the engine controller. These algorithms arerequired for any vehicle, regardless of the type and number of torquegenerators, and are not therefore engine specific. Another example ofalgorithms routinely integrated into the engine controller is passiveanti-theft algorithms. By not purposely distinguishing these algorithmsfrom the base engine control algorithms, modular design, testing andimplementation of the control system becomes much more difficult.

A second problem with conventional engine controllers is that many ofthe algorithms in the engine controller are engine system centric. Sincethe engine controller has historically been the predominant controllerin the vehicle, many algorithms have been written assuming that theengine specific information is always available. For example, theinterface between the transmission and engine control functions used fortorque reduction during shifting is written in terms of spark anglerather than torque. This type of architecture is not conducive to addingother torque producing devices to the drive line such as, for example,an electric motor.

At the same time that engine control systems have been growing incomplexity, control systems have been added to other subsystems on thevehicle with the intention of improving various aspects such as safety,durability, performance, emission control and the like. Typically, thesecontrol systems are implemented as stand alone systems that providelittle or no interaction with the other control systems on the vehicle.

New vehicle technologies such as hybrid electric power trains, advancedengines, active suspensions, telematics, and the like are increasinglyincorporated into the vehicle. As these technologies emerge and aretargeted towards production vehicles, the interaction between subsystemsgrows ever more complex. To achieve increasingly more stringentrequirements on vehicle objectives for emissions, safety, performance,and the like, the interactions between major subsystems in the vehicleneed to be coordinated at the vehicle level.

Interactions between separate subsystems is particularly troublesomewhen coordinating rapidly changing torque requests between separatesubsystem controllers. For example, the traditional engine-centriccontroller cannot make fast torque decisions for non-engine torqueproducing components.

What is needed is a functional structure that allows several torqueproducing devices to be coordinated at the vehicle level. This structureshould be flexible, permitting application in a wide variety of vehicleconfigurations. In addition, this structure should be readilyimplemented in current and future vehicle control systems.

SUMMARY OF INVENTION

Traction requests are resolved into base requests and fast requestsdepending upon response times of torque devices satisfying theserequests. At least one fast torque request is coordinated based on atleast one base request.

One advantage of the present invention is improved control resultingfrom common torque request coordination. This coordination yieldsimproved fuel economy, improved driveability and reduced emissions.

A method for coordinating rapidly changing torque demand in anautomotive vehicle having an engine and at least one motor is provided.An engine base torque level indicating slowly changing torque producedby the engine is received. A request for fast desired torque is alsoreceived. A motor torque is determined as a difference between the fastdesired torque and the engine base torque level. An engine fast torqueis determined as a difference between the request for fast desiredtorque and the motor torque. A motor torque request is determined as themotor torque and an engine torque request is determined as the enginefast torque.

In an embodiment of the present invention, determining the motor torqueincludes limiting the difference between the fast desired torque and theengine base torque level by at least one motor torque availabilitylimitation.

In another embodiment of the present invention, the engine torquerequest is determined as a base engine torque request if the base enginetorque request is less than the engine fast torque.

In still another embodiment of the present invention, the motor torqueis limited with at least one motor slew rate limitation prior todetermining the engine fast torque.

An indicator as to the source of the request for fast desired torque maybe received. Possible sources include a traction control torque requestand a transmission torque modulation request.

A request for intended motor torque may be received. The motor torquerequest may be determined as the request for intended motor torque ifthe source of the request for fast desired torque does not match one ofthe at least one allowable fast desired torque requesters. The motortorque request may be determined as the motor torque only if the sourceof the request for fast desired torque matches one of at least oneallowable fast desired torque requesters.

In a further embodiment of the present invention, a base engine torquerequest is received. The engine torque request is determined as the baseengine torque request if the source of the request for fast desiredtorque does not match one of the at least one allowable fast desiredtorque requesters.

A vehicle having an engine and at least one motor is also provided. Theengine supplies engine torque to drive the vehicle based on an enginetorque request. Each motor supplies motor torque to drive the vehiclebased on a motor torque request. The vehicle includes various torquerequesting sources. Control logic receives an engine base torque levelindicating slowly changing torque produced by the engine and receives arequest for fast desired torque. A motor torque is determined as adifference between the fast desired torque and the engine base torquelevel as limited by at least one motor torque availability limitation.An engine fast torque is determined as a difference between the requestfor fast desired torque and the motor torque. The motor torque requestis determined based on the motor torque and the engine torque request isdetermined based on the engine fast torque.

A method for controlling a motor vehicle having a plurality of torqueproducing sources for propelling the vehicle is also provided. A basetorque level indicating slowly changing torque produced by a firstpropelling torque source is received. A second propelling source torquerequest is determined based on a difference between a fast desiredtorque and the base torque level as limited by at least one secondpropelling source torque availability limitation. A first propellingsource torque request is determined based on a difference between therequest for fast desired torque and the second propelling source torquerequest.

The above objects and other objects, features, and advantages of thepresent invention are readily apparent from the following detaileddescription of the preferred embodiments for carrying out the inventionwhen taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating torque producing devicesaccording to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating multilevel torque resolutionaccording to an embodiment of the present invention;

FIGS. 3 a and 3 b are a block diagram illustrating motion controlfunctions for an integrated starter-generator hybrid vehicle accordingto an embodiment of the present invention;

FIGS. 4 a-4 c are block diagrams illustrating a generalized architecturefor vehicle motion control according to an embodiment of the presentinvention;

FIG. 5 is a schematic diagram illustrating a vehicle with electricfour-wheel drive according to an embodiment of the present invention;

FIGS. 6 a and 6 b is a block diagram illustrating a vehicle motioncontroller for electric four-wheel drive according to an embodiment ofthe present invention;

FIG. 7 is a block diagram illustrating wheel level torque coordinationaccording to an embodiment of the present invention;

FIG. 8 is a block diagram illustrating transmission input level basetorque coordination according to an embodiment of the present invention;

FIG. 9 is a block diagram illustrating fast torque coordination at thetransmission input level according to an embodiment of the presentinvention;

FIG. 10 is a block diagram illustrating arbitration among base requestsat the wheel level according to an embodiment of the present invention;

FIG. 11 is a block diagram illustrating arbitration at the transmissioninput level according to an embodiment of the present invention; and

FIG. 12 is a block diagram illustrating multilevel torque resolutionaccording to an embodiment of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a schematic diagram illustrating torque producingdevices according to an embodiment of the present invention is shown.Vehicle 20 may include a plurality of torque producing devices. Torqueproducing devices include any of a wide variety of internal combustionengines (ICE). Various types of motors may also be employed, includingthose powered by energy storage devices such as batteries, accumulatorsand the like; powered by power generating devices, such as engines, fuelcell systems, solar cell systems, and the like; or powered by anycombination of these.

For example, engine 22 transmits torque through engine transmission 24to front axle 26 thereby driving wheels 28. Engine transmission 24 iscontrolled to convert torque from engine 22 to axle 26 using variousmechanisms such as torque converters, gears, and the like. Transmission24 may be manual, automatic, continuously variable, composed of one ormore planetary gear sets, or of any other suitable construction oroperation. Vehicle 20 may also include electric motor 30 mechanicallyconnected to engine transmission 24. Motor 30 may be, for example, anintegrated starter-generator (ISG). Engine 22 may be connected to motor30 through clutch 31. Disengaging clutch 31 allows motor 30 to driveaxle 26 without driving engine 22. Various torque producing devices maybe interconnected by one or more of a variety of mechanisms, includingmechanical coupling, electromagnetic coupling, hydraulic coupling, andthe like. Vehicle 20 may also include motor 32 connected through anintermediate stage of engine transmission 24 to axle 26.

Many alternative drive configurations are possible. For example,internal combustion engine 33 transmits torque through transmission 34to rear axle 36 propelling wheels 28. Electric motor 38 transmits torquethrough separate transmission 40 to rear axle 36. Transmission 40 mayalso transmit torque from rear axle 36 to motor 38 when motor 38 isgenerating electric power. One or more motor/generators 42 may also bedirectly connected to axle 36. Motor/generators 42 may be electric orhydraulic, the latter storing energy in accumulators during decelerationfor later delivery to wheels 28 for acceleration. Various combinationsof front drive and/or rear drive sources can be implemented. Inaddition, any number of axles or other output shafts may be driven. Thepresent invention is not limited to a specific configuration of drive ortorque generating devices.

Vehicle 20 typically includes at least one mechanism for decelerating.Each wheel 28 may include one or more friction brake 44. Engine 22, 33may implement compression braking. Motor 30, 32, 38, 42 may implementregenerative braking.

Vehicle 20 with a multitude of torque producing devices is moreefficiently controlled through a coordinated effort to receive torquerequests and generate torque commands. A multilevel consideration isappropriate since torque producing devices and torque requesting sourcesoperate at different levels. For example, some torque producing devicesoperate at a transmission input level whereas other torque producingdevices operate at a transmission output or wheel level. Similarly,torque requests may be received at either the transmission input orwheel levels. It should be noted that the term transmission generallyrefers to any means for converting torque such as gears, belts, torqueconverters, clutches, shafts, pulleys, and the like, as well astraditional engine transmissions.

Referring now to FIG. 2, a block diagram illustrating multilevel torqueresolution according to an embodiment of the present is shown. A levelmay be any point in a drive train where torque is requested orgenerated. Possible levels include at a wheel, axle, transmission input,transmission output, intermediate transmission stage, power take-offpoint, and the like.

An exemplary torque resolution system, shown generally by 50, operateson both wheel level 51 and transmission input level 52. Wheel levelresolver 53 receives a plurality of wheel level torque requests 54 andgenerates at least one of wheel level base requests 55 and wheel levelfast requests 56. Wheel level resolver 53 may also coordinate wheellevel requests 55, 56 between wheel level torque producing devices.

Operation at wheel level 54 may be expressed in one or more of a varietyof reference domains. These domains apply to both vehicle accelerationand deceleration. The wheel torque domain expresses variables in termsof the torque requested at, or delivered to, one or more wheels 28. Thedrive shaft domain is related to the wheel torque domain throughdifferential gear ratios. The tractive force domain is related to thewheel torque domain through the wheel radius. The vehicle accelerationdomain is related to the tractive force domain through vehicle mass. Thepresent invention applies regardless of which domain is considered.Without loss of generality, operation at the wheel level will bedescribed in terms of wheel torque.

Translator 57 accepts wheel level base requests 55 and wheel level fastrequests 56 and translates requests 55, 56 to compensate for the effectof any torque conversion between transmission input level 52 and wheellevel 51. Translator 57 generates translated base requests 58 andtranslated fast requests 59 by translating wheel level base requests 55and wheel level fast requests 56, respectively.

Transmission input level resolver 60 accepts translated base requests58, translated fast requests 59 and transmission input level requests61. Transmission input level resolver 60 arbitrates requests 58, 59, 61to produce transmission input level base requests 62 and transmissioninput level fast requests 63. Transmission input level resolver 60 mayalso coordinate torque requests 62, 63 between multiple transmissioninput level torque producing devices.

One aspect of the present invention is that torque may be arbitrated attwo or more levels. For example, wheel torque and transmission inputtorque are arbitrated separately by torque resolution system 50. Thefirst arbitration compares all wheel torques that are requested at wheellevel 51. After drive line disturbance control, the desired value ofwheel torque is translated or converted to a desired crankshaft torqueby adjusting for transmission torque ratio and losses. Since this is thepoint in vehicle 20 at which torque is summed on the drive line, it isan appropriate place for the second arbitration to occur. Here, allrequests for crankshaft (transmission input) torque, including thearbitrated and translated wheel torque, are arbitrated to determine afinal desired crankshaft torque.

A second aspect of the present invention propagates arbitrated desiredtorque requests into two signals: a base value and a fast value. As willbe recognized by one of ordinary skill in the art, there are severalways to affect the torque in vehicle 20. Thus, an effort is made todistinguish between base requested values, associated primarily withmeeting driver demand and other relatively slow requests within thesystem, from fast values related to vehicle subsystem protection,safety, and other high speed requests for torque. This dichotomy alsoconveniently reflects the variation and abilities to produce torquewithin an engine. An internal combustion engine has methods formodifying torque that can cover the entire range of operation such as,for example, air flow modification, that typically have a low responsetime. These methods are best used for achieving base torque response.The internal combustion engine can also modify torque rapidly but oftenwithin only limited authority such as, for example, in sparkmodification. Similarly, an ISG is another device that can produce fasttorque response within only limited torque capability. These types oftorque production are best matched with fast torque demands.

Translator 57 may implement a fixed algorithm or a variable algorithmdepending on the operation and type of transmission represented bytranslator 57. For example, engine transmission 24 may be represented bytranslator 57 implementing, for each fast and/or slow torque, thefollowing formula: τ_(c)=rFm+y, where τ_(c) is a transmission inputtorque as represented by translated wheel level base requests 58 ortranslated wheel level fast requests 59, r is an effective wheel rollingradius, F is a traction force representing wheel level base requests 55or wheel level fast requests 56, m is a torque ratio, and y is a torqueoffset. In addition, while only one translator 57 is shown in FIG. 2, aplurality of translators 64 may be used if multiple transmissionsconvert torque within vehicle 20. Examples of other levels between whichtranslation may occur include differential input, planetary gear stages,and the like.

Referring now to FIGS. 3 a and 3 b, a block diagram illustrating motioncontrol functions for an integrated starter-generator (ISG) hybridvehicle according to an embodiment of the present invention is shown. Avehicle system controller, shown generally by 70, contains the set ofdistinguishing characteristics for torque control in vehicle 20. Vehiclesystem controller 70 also coordinates the interactions of varioussubsystems in vehicle 20 as represented by transmission controller 72,battery controller 74, ISG controller 76, and engine controller 78.Vehicle system controller 70 is preferably implemented on amicrocontroller system within vehicle 20. As will be recognized by oneof ordinary skill in the art, functions performed by vehicle systemcontroller 70 may be implemented in more than one special purposecontroller, may be split amongst other vehicle controllers, and mayimplement functionality that may otherwise be assigned to various othervehicle controllers. Functionality in vehicle system controller 70 maybe implemented as hardware, software, firmware, or any combination.

Vehicle system controller 70 may be divided into a plurality offunctional elements, as illustrated here by way of example. Acceleratorpedal interpreter 80, vehicle speed limiting 82, and cruise control 84generate wheel level torque requests. Accelerator pedal interpreter 80accepts accelerator pedal position 86 and vehicle speed 88 anddetermines driver's desired tractive force 90. Cruise control 84 acceptsdesired vehicle speed 92 and vehicle speed 88 and determines cruisedesired tractive force 94 needed to maintain a desired vehicle speed.Vehicle speed limiting 82 determines maximum tractive force 96 as alimit needed to avoid vehicle overspeed condition. Tractive forcearbitration 98 accepts desired tractive forces 90, 94 and maximumtractive force 96. Tractive force arbitration 98 arbitrates requests fortractive force from these various sources and generates desired tractiveforce base. Desired tractive force base 100 is a wheel level baserequest.

Tractive force arbitration 98 also generates tractive force source 104propagated along with base desired tractive force 100. Tractive forcesource 104 provides an indication of the requirements of the torquecommand and is used to help the torque and speed coordination functionand torque producing subsystems to determine the appropriate method forachieving the desired torque values. For example, engine 22 can producea fast torque reduction by either modifying spark advance or fuel cutoffto cylinders. The utility of these two methods varies, however, as sparkis limited in the range of reduction that can be achieved whereas fuelis limited in the precision of the torque reduction produced. Byencoding either the source of the torque request or the desired affectof the request in tractive force signal 104, torque and speedcoordination function and torque producing subsystems can make betterdecisions as to the appropriate course of action.

Max/min crankshaft torque 106 determines total minimum and maximumavailable crankshaft torque from all sources. In this example, inputsinclude ISG max/min torque available 108 from ISG controller 76 andengine max/min torque available 110 from engine controller 78. Max/mincrankshaft torque 106 generates max/min available crankshaft torque 112.Shift scheduling 114 accepts accelerator pedal position 86, vehiclespeed 88, and max/min available crankshaft torque 112. Shift scheduling114 determines transmission configuration as desired gear signal 116 totransmission controller 72. Converter clutch scheduling 118 determinesthe desired lock up status of the torque converter bypass clutch basedon accelerator pedal position 86 and vehicle speed 88. Specifically,converter clutch scheduling 118 generates desired converter clutch stateand desired converter clutch slip 119 for transmission controller 72.Transmission controller 72 controls clutch and valve solenoids withinengine transmission 24. Transmission controller 72 also generates avariety of signals including torque ratio and torque loss offsetsignals, shown generally by 120, used for translating torque requests.Signal 122 from transmission controller 72 indicates the maximum andminimum crankshaft fast torque and maximum crankshaft base torque.Signal 124 indicates transmission stop permission and signal 126indicates desired crankshaft speed.

Block 128 performs translation down through engine transmission 24.Actual crankshaft torque 130 is translated using torque ratio and torqueloss offset signals 120 to produce actual tractive force 132. Drivelinedisturbance control 134 accepts desired tractive force base 100 andactual tractive force 132 to smooth driveline responses to rapid changesin torque demand. The result is filtered desired tractive force base136.

Block 140 translates desired tractive force to desired crankshafttorque. Filtered desired tractive base force 136 is translated usingtorque ratio and torque loss offset signals 120 to produce translateddesired tractive force base 142.

Crankshaft torque arbitration 146 accepts translated desired tractiveforce base 142 and tractive force source 104 as well as requests ofcrankshaft torque from any other source. Crankshaft torque arbitration146 arbitrates these requests to generate desired crankshaft torque base148, desired crankshaft torque fast 150, and crankshaft torque source152 reflecting tractive force source 104.

Referring now to FIG. 3 b, energy management block 154 represents energymanagement functions of vehicle system controller 70. Energy management154 generates desired generation power 156 and energy management stopokay flag 158. Driveline idle speed coordination 160 accepts desiredgeneration power 156 and desired crankshaft speed 126 to determine thedesired operating speed for driveline during periods without driverdemand. This desired operating speed is expressed as desired idle speed162 used by engine controller 78.

Torque and speed coordination function 174 splits requested torquebetween various torque producers. In this example, torque producers areinternal combustion engine 22 and ISG motor 30 as controlled by enginecontroller 78 and ISG controller 76, respectively. Torque and speedcoordination 174 accepts desired crankshaft torque base 148, desiredcrankshaft torque fast 150, and crankshaft torque source 152 fromcrankshaft torque arbitration 146. Inputs also include transmission stopokay flag 124, energy management stop okay flag 158, ISG stop okay flag166 from ISG controller 76, engine stop okay flag 168 from enginecontroller 78, battery stop okay flag 170 from battery controller 74,and desired generation power 156. ISG controller 76 receives desired ISGtorque, desired ISG speed, and ISG torque or speed control mode,represented by signals 184, from torque and speed coordination 174.Engine controller 78 receives desired engine torque base, desired enginetorque fast, and engine torque source, represented by signals 186, fromtorque and speed coordination 174. Energy management 154 receivesdesired crankshaft torque base and desired crankshaft torque fast,represented by signals 188, from torque and speed coordination 174.

Referring now to FIGS. 4 a-4 c, block diagrams illustrating ageneralized architecture for vehicle motion control according to anembodiment of the present invention are shown. In certain applications,there is a need to coordinate torque requests at the wheels. Examples ofsuch applications include when electro-hydraulic brakes (EHB) are usedto more efficiently capture braking energy, when a traction motor isintroduced on an axle not driven by an internal combustion engine toprovide four-wheel drive functionality, and the like. A generalizedarchitecture covers the case where some propelling devices apply torqueto the crankshaft/output shaft, with this torque passed through one ormore typically variable transmissions before reaching the wheels, andother devices apply torque directly coupled to the wheels. An example ofsuch an architecture is an electric four-wheel drive system with one ormore electrical motors applying power directly to an axle or wheel.

Referring now to FIG. 4 a, wheel level torque resolution is illustrated.Speed control arbitration function 240 accepts accelerator desired wheelforce 242 from driver evaluator and wheel force limit signals 244 fromvehicle speed control and produces desired wheel force 246. Front torquetranslation 248 uses front transmission parameters 250 to convert frontcrankshaft torque 252 to front tractive force 254. Rear torquetranslation 256 uses rear transmission parameters 258 to convert rearcrankshaft torque 260 to rear tractive force 262.

Anti-jerk control 264 filters desired wheel force 246, front tractiveforce 254, rear tractive force 262, and other slowly changing tractiverequests such as driver evaluator signals 266, engine controller signals268, transmission controller signals 270, and the like. Anti-jerkcontrol 264 generates base tractive force requests 272 which aremultiplied by one or more wheel constants 274 to produce accelerationtorque requests 276. Acceleration torque requests 276, braking torquerequests 278 from a braking controller, and vehicle speed signal 280 arecombined in calculation block 282 to produce overall vehicle desiredtorque signal 284. Wheel torque arbiter 286 accepts overall vehicledesired torque signal 284 together with fast acting torque requests 288from the brake controller. Fast brake signals 288 are generated bycomponents including anti-lock brake systems (ABS), stability andtraction control (STC), interactive vehicle dynamics (IVD), and thelike. Torque vehicle speed limit 290 provides allowable torque limits.Wheel torque arbiter 286 generates wheel level base requests 292 andwheel level fast requests 294.

Signals along the interface among functions can be either scalars orvectors. For example, fast brake signals 288 can be expressedindividually for each wheel or for each axle. The respective signals canthen be propagated as vectors and considered individually for torquecoordination.

Wheel torque coordinator 296 distributes torque requests between fronttorque request base 298, front torque request fast 300, rear torquerequest base 302 and rear torque request fast 304. Front brake torqueintent 306 and rear brake torque intent 308 are nonzero only duringbraking. Braking controlled torque distribution 310 accepts front braketorque intent 306, rear brake torque intent 308, wheel level fastrequests 294 and internal brake subsystem controller signals andgenerates brake torque requests 312 for the brake controller, as well asfront axle torque limits 314 and rear axle torque limits 316. Wheeltorque coordinator 296 accepts as input various torque requestsincluding wheel level base requests 292, wheel level fast requests 294,front generator torque requests at the wheel level 318, and reargenerator torque requests at the wheel level 320. Wheel torquecoordinator 296 also accepts torque limits including front axle torquelimit 314, rear axle torque limit 316, front motor torque availabilitylimit 322, front engine torque availability limit 324, rear motor torqueavailability limit 326, and rear engine torque availability limit 328.Not all of these signals will be present in every application.

Referring now to FIG. 4 b, front crankshaft input level torqueresolution is illustrated. Front torque translator 340 uses fronttransmission parameters 342 such as gear ratios, torque ratios,transmission internal losses and the like, to translate front torquerequest base 298 and front torque request fast 300 to translated wheellevel front torque request base 344 and translated wheel level fronttorque request fast 346, respectively. Front crankshaft torquearbitration 348 arbitrates translated wheel level front torque requestbase 344 and fast 346 with limits such as torque limit during shift 350from front transmission controller resulting in transmission input levelfront torque request base 352 and fast 354, respectively.

Front axle torque coordinator 356 distributes torque requests amongfront axle torque producing devices. To this end, front axle torquecoordinator 356 generates base and fast engine torque requests 358 for afront engine controller and motor torque requests 360 for a front motor.In addition front axle torque coordinator 356 generates front generatortorque request at the wheel level 318 and actual front crankshaft torque252. Front axle torque coordinator accepts requests such as transmissioninput level front torque request base 352 and fast 354 and electricalpower generation torque request 362 from generation torque requester 364based on energy management front generated power request 366 and enginespeed idle target 368 from front engine controller. Front axle torquecoordinator 356 distributes torque requests based on availabilities andcapabilities of torque producing devices as represented, for example, byengine torque capability signal 370 and front motor torque availabilitysignal 372.

Front motor torque availability signal 372 is generated by motoravailability logic 374 based on state of charge signal 376 from anenergy storage management module and torque capacity signal 378 from afront motor control. Engine torque capability signal 370 and front motortorque availability signal 372 are translated by front down torquetranslator 380 based on front transmission parameters 342 to generatefront engine torque availability limit 324 and front motor torqueavailability limit 322, respectively.

Referring now to FIG. 4 c, rear transmission level torque resolution isillustrated. In the general case, rear transmission level torqueresolution operates fundamentally the same as front transmission leveltorque resolution. Rear torque translator 390 uses rear transmissionparameters 391 such as gear ratios, torque ratios, transmission internallosses and the like, to translate rear torque request base 302 and reartorque request fast 304 to translated wheel level rear torque requestbase 392 and translated wheel level rear torque request fast 393,respectively. Rear crankshaft torque arbitration 394 arbitratestranslated wheel level rear torque request base 392 and fast 393 withlimits such as torque limit during shift 350 from rear transmissioncontroller resulting in transmission input level rear torque requestbase 396 and fast 398, respectively.

Rear axle torque coordinator 400 accepts rear transmission input leveltorque request base 396 and fast 398, rear electrical power generationtorque request 402 based on rear generated power request 404, as well asengine torque capability signal 405 and rear motor torque availabilitysignal 406. Rear axle torque coordinator 400 generates base and fastengine requests 408, motor torque requests 410, rear generator torquerequests at the wheel level 320, and rear crankshaft torque signals 260.Rear motor torque availability signal 406 is generated by motoravailability logic 412 based on torque capacity signal 414 from rearelectric motor controller. Rear down torque translator 416 translatesrear motor torque availability signal 406 and engine torque capabilitysignal 405 into rear motor torque availability limit 326 and rear enginetorque availability limit 328.

Referring now to FIG. 5, a schematic diagram illustrating a vehicle withelectric four-wheel drive according to an embodiment of the presentinvention is shown. Vehicle 430 includes front axle 432 and rear axle434. Internal combustion engine 436 and integrated starter-generator(ISG) 438 are coupled to rear axle 434 through automatic enginetransmission 440. Traction motor 442 is either directly coupled to frontaxle 432 or coupled to front axle 432 through a fixed transmission, theeffects of which may be ignored without loss of generality.

Torque control within vehicle 430 is distributed amongst a plurality ofmodules. Engine controller (EC) 444 controls various engine functionsincluding spark, air, fuel, cam timing, exhaust gas recirculationcontrol, and the like. Engine controller 444 provides indications of themaximum and minimum engine torque available. Rear electric motorcontroller (REM) 446 provides control signals to ISG 438. Transmissioncontroller (TC) 448 provides clutch and valve solenoid control fortransmission 440. Front electric motor control (FEM) 450 providescontrol signals to traction motor 442. Brake control 452 handles brakingfunctions such as actuation for hydraulic brakes 454, anti-lock brakecontrol, and the like. Battery management module (BMM) 456 providesstate of charge and state of health estimation and current and voltagelimit calculations, as well as actual voltage and current measurements.Vehicle speed control (SC) 458 provides cruise control and maximumallowed vehicle speed-based torque limits. Driver evaluator (DE) 460provides signals based on driver input. Vehicle system controller (VSC)462 provides top level torque resolution for vehicle 430. Sensors 464 onaxles 432, 434 provide axle rotation information to wheel slipcontroller 466 for balancing wheel speeds. As will be recognized by oneof ordinary skill in the art, one or more of the modules illustrated maybe implemented with the same hardware. Further, functions attributed toeach module may be divided amongst various hardware components.

Referring now to FIGS. 6 a and 6 b, a block diagram illustrating avehicle motion controller for electric four-wheel drive according to anembodiment of the present invention is shown. Vehicle system controller462 implements logic to arbitrate between torque requests and coordinaterequest distribution amongst torque producing devices. The logicillustrated in FIG. 6 is similar to the generalized logic illustrated inFIGS. 4 a-4 c.

Various wheel level torque requests are filtered, combined, limited, andotherwise arbitrated to produce wheel level base requests 292 and wheellevel fast requests 294. Additional inputs include four-by-four requestinterpreter signal 470 for balancing axle or wheel speeds. Wheel torquecoordinator 296 generates rear torque request base 302 and rear torquerequest fast 304 which are translated by rear torque translator 390. Nosuch translation may be required for traction motor 442 driving frontaxle 432. If translation is required, the translation is fixed. Thus,wheel torque coordinator 296 generates wheel level torque request signal472 for front electric motor controller 450.

Referring now to FIG. 7, a block diagram illustrating wheel level torquecoordination according to an embodiment of the present invention isshown. In most hybrid configurations, there is a need for torquecoordination function at wheel or axle level 52. Inputs to such acoordination function include arbitrated at wheel level torque requestsfor the vehicle as a whole, torque requests for individual axles, torquerequests for individual wheels, driver demand information, andlimitations from various sources such as vehicle stability, and thelike. In addition, inputs should include torque capabilities andlimitations of devices applying torque to the wheels either directly ortranslated through a transmission. The coordination function prioritizestorque application sources based on driver requirements, efficiencyconsiderations, performance considerations, and the like. Torquecoordination effectively funnels torque requests through torqueavailability limits in a priority order. This results in the issuance oftorque commands to torque producing devices within the capability ofthese devices.

The embodiment illustrated in FIG. 7 implements torque coordination atthe wheel level for an electric four wheel drive vehicle as depictedschematically in FIG. 5. Electric motor 442 drives front axle 432 andinternal combustion engine 436 provides torque through transmission 440to rear axle 434.

A wheel level torque coordinator, shown generally by 480, acceptsarbitrated torque request 482. Wheel level torque coordinator 480 mayaccept additional torque requests as well. In the embodiment shown,requests include 4×4 torque request 484 for regulating axle speeds andgenerator torque request 486 from energy management controller 154.Selector 488 passes inverted 4×4 torque request 484 as auxiliary torquerequest 490 if 4×4 torque request 484 is non-zero. Otherwise, selector488 passes generator torque request 486 as auxiliary torque request 490.

Auxiliary torque request 490 is added to arbitrated torque request 482in summer 492 to produce summed torque 494. Since auxiliary torquerequest 490 is either the negative of 4×4 torque request 484 orgenerator torque request 486, which can be a negative requested torque,summed torque request 494 may be less than arbitrated torque request482.

Engine maximum torque limit 496 and engine minimum torque limit 498provide inputs to engine torque limiter 500. Engine torque limiter 500outputs initial coordinated torque request 502 as summed torque request494 limited by engine maximum torque limit 496 and engine minimum torquelimit 498. Differencer 504 subtracts initial coordinated torque request502 from arbitrated torque request 482 to produce first excess requestedtorque 506. First excess requested torque 506 represents requestedtorque in excess of the capability of engine 436.

Motor torque limiter 508 accepts motor maximum torque limit 510 andmotor minimum torque limit 512 representing torque limits for electricmotor 442. Motor torque limiter 508 outputs front axle torque request514 as first excess requested torque 506 limited by motor maximum torquelimit 510 and motor minimum torque limit 512. Differencer 516 subtractsfront axle torque request 514 from first excess requested torque 506 toproduce second excess requested torque 518. Second excess requestedtorque 518 indicates requested torque which cannot be handled byelectric motor 442.

Summer 520 adds initial coordinated torque request 502 and second excessrequested torque 518 to produce coordinated torque request 522. Reartorque limiter 524 generates rear axle torque request 526 by limitingcoordinated torque request 522 with engine maximum torque limit 496 andengine minimum torque limit 498.

Wheel level torque coordinator 480 may be used to implement a widevariety of torque coordinating functions. For example, power assist isprovided whenever powertrain wheel torque requests, as represented byarbitrated torque request 482, exceed the torque availability estimatedfor engine 436 at the wheels. The excess request will be directed totraction motor 442 through front axle torque request 514.

Another function is 4×4 balancing. 4×4 torque request 484 represents theneed to regulate to zero the difference in speeds between front axle 432and rear axle 434. In this situation, arbitrated torque request 482 issubtracted from the engine torque request and added to the motor torquerequest. Effectively, the request for engine torque is reduced by 4×4torque request 484 and the request to front axle traction motor 442 isincreased by 4×4 torque request 484. This redistributes torque betweenthe axles for better vehicle traction without the need for driverintervention.

Another function is charging through the road. In the absence of a 4×4request and in the event of a low state of charge on the high voltagebattery, traction motor 442 can be used to charge the battery. This isaccomplished by increasing the torque request to engine 436 andsubtracting this increase from the torque requested to traction motor442. This effectively requests motor 442 to apply negative torque. Thisnegative torque converts traction motor 442 into a generator forcharging the battery.

Yet another function is regenerative braking. During a braking maneuver,powertrain wheel torque request 482 will have a negative sign. Aftersubtracting the effect of engine compression braking at the wheels, ifany, the remainder of the powertrain request is sent to electric motor442. Electric motor 442 applies negative torque within its torqueavailability and within the state of battery charge. Remaining brakingtorque may be provided by foundation brakes.

Still another function is bleed through the road. In the event of a veryhigh battery state of charge, battery energy may be depleted to createroom for future regenerative events by using motive torque from motor442 in parallel with engine 436. The energy management function sends anegative torque request as generator torque request 486. This negativerequest effectively reduces the torque command to engine 436 andincreases the torque command to motor 442, thus using excess batteryenergy

Wheel level torque coordinator 480 may be used to calculate powertrainbraking torque requests. Rear axle torque request 526 is multiplied byvehicle rolling direction 530 in multiplier 532. Vehicle rollingdirection 530 has a value of 1.0 if vehicle 430 is traveling in aforward direction and a value of −1.0 if vehicle 430 is traveling in areverse direction. Rear powertrain brake torque request 534 is theoutput of multiplier 532 if this output is less than zero and is zerootherwise. Similarly, front axle torque request 514 is multiplied byvehicle rolling direction 530 in multiplier 536. Front powertrain braketorque request 538 is the output of multiplier 536 if this output isless than zero and is zero otherwise.

Torque limits within wheel level torque coordinator 480 may each bebased on one or more torque limitation inputs. In the embodiment shown,engine maximum torque limit 496 is the minimum of wheel level maximumengine torque capability 540 and rear axle maximum torque 542. Engineminimum torque limit 498 is the maximum of wheel level minimum enginetorque capability 544 and rear axle minimum torque 546. Motor maximumtorque limit 510 is the minimum of wheel level maximum motor torquecapability 548 and front axle maximum torque 550. Motor minimum torquelimit 512 is the maximum of wheel level minimum motor torque capability552 and front axle minimum torque 554.

Referring now to FIG. 8, a block diagram illustrating transmission inputlevel base torque coordination according to an embodiment of the presentinvention is shown. A transmission input level torque coordinator, showngenerally by 560, accepts crankshaft desired base torque 562 andgenerator requested torque 564. Crankshaft desired base torque 562 andgenerator requested torque 564 are added in summer 566 to producecombined requested torque 568. Limiter 570 produces initial coordinatedtorque request 572 by limiting combined requested torque 568 with enginemaximum torque limit 574 and engine minimum torque limit 576.

Initial coordinated torque request 572 is subtracted from crankshaftdesired base torque 562 by differencer 578 to produce first excessrequested torque 580. Limiter 582 generates coordinated motor request584 by limiting first excess requested torque 580 with motor maximumtorque limit 586 and motor minimum torque limit 588. Coordinated torquerequest 590 is generated in summer 592 by subtracting coordinated motorrequest 584 from the sum of initial coordinated torque request 572 andfirst excess requested torque 580. Limiter 594 generates coordinatedengine base request 596 by limiting coordinated torque request 590 withengine maximum torque limit 574 and engine minimum torque limit 576.

Torque coordination may also include a variety of functions such aspower assist, regenerative braking, charging, bleed, and the like.

Referring now to FIG. 9, a block diagram illustrating fast torquecoordination at the transmission input level according to an embodimentof the present invention is shown. In this embodiment, fast torquecoordination is selected only for certain types of fast requests. A fasttorque coordinator, shown generally by 610, receives arbitration winner612 from one or both of wheel level arbitration and transmission inputlevel arbitration. If arbitration winner 612 equals either tractioncontrol torque request 614 or transmission torque modulation request616, then binary match flag 618 is set. As will be described in greaterdetail below, binary match flag 618 is a control signal selectingoutputs for fast torque coordinator 610.

Actual engine base torque 620 is subtracted from desired fast torque 622in differencer 624 to produce initial fast torque request 626. Limiter628 generates limited fast torque request 630 by limiting initial fasttorque request 626 with maximum available motor torque 632 and minimumavailable motor torque 634. If binary match flag 618 is not asserted,base intended motor torque 636 is output as motor torque request 638. Ifbinary match flag 618 is asserted, limited fast torque request 630 isoutput as motor torque request 638.

Limiter 640 uses motor slew rate 642 to represent the dynamic responseof the electric motor for estimating transient motor torque output. Thisvalue is subtracted from desired fast torque 622 to produce desiredengine fast torque 644. If binary match flag 618 is asserted, enginetorque request 646 is the minimum of desired engine fast torque 644 andengine requested base torque 648. If binary match flag 618 is notasserted, engine torque request 646 is simply engine requested basetorque 648.

Conventional, non-hybrid vehicles with automatic or automated shiftmanual transmissions have a large degree of interaction between theengine and transmission control systems. One of these interactions istorque modification requested of the engine by the transmissioncontroller prior to and during a shift event. This modulation, typicallya torque reduction, improves the quality or feel of the shift andprotects the internal transmission components.

Typically, the engine controller has several options to achieve therequested torque modulation. Spark timing modification has generallybeen preferred over air or fuel modulation for a number of reasons.Although air modulation has the benefit of a wide range of authoritywith respect to torque command, the response time of the engine due tochanges in air command are too slow to effectively modify the torque inthe time required for the shift. Torque changes due to spark timingmodification, on the other hand, are nearly instantaneous due to thedirect impact of spark on combustion. Spark control is also preferableto fuel cut out due to the granularity of control associated with thefuel command. This is particularly true for individual cylinder fuelinjection where the amount of fuel injected must be kept in proportionto the amount of air in the cylinder. Thus, torque can only be reducedby cutting out individual cylinders completely. This results in limited,discrete levels of torque production that are not sufficient toadequately control torque during shifting. Spark control has theadvantage that continuous change in spark angle results in continuouschange in the torque produced by the engine.

The use of spark angle modification for torque modulation does, however,have several disadvantages. First, the range of torque authority fromspark control is limited to only about 30% of the current level oftorque being produced. This directly limits the level of reduction thatthe transmission can request during a shift. Also, since the spark angleis normally commanded as closely as possible to that angle which wouldproduce maximum level of brake torque (MBT) production from the engine,there is no opportunity to provide a torque increase using spark angle.Another problem related to moving the spark angle away from MBT timingfor the purpose of torque modulation is that the efficiency ofcombustion is lower as more fuel is converted to heat rather than usedto produce torque. This results in a slight fuel economy degradation forthe vehicle. Finally, by moving away from MBT timing, there is anincrease in the emissions produced by the engine as less of the fuel isburned in the cylinder.

The addition of electric motor 442 to the drive line provides anadditional option for achieving torque modulation during shifting.Electric motor 442 provides several advantages over spark timing whenused for torque modulation. Given that the normal request fromtransmission controller 448 is for torque reduction, electric motor 442may achieve the torque reduction by providing a positive chargingcurrent to the battery. Whereas spark modification results in a netenergy loss in the system, use of motor 442 results in an energy gain,thereby increasing fuel economy. In addition, motor 442 can be used toprovide positive torque increases if requested by the transmission 440.Such a torque increase is not readily available from typical sparktiming control due to the use of MBT spark timing. The availability ofpositive torque modification potentially results in smoother shifts.Because motor 442 has a response time similar to that of spark timingcontrol, no adverse delay is introduced.

For these reasons, it is desirable to use motor 442 for torquemodulation whenever possible. There are a few limitations related tomotor 442 that must be taken into account. For example, the availabletorque from motor 442 can be limited by several factors including motortemperature, battery state of charge, motor speed, and the like. Incases where motor torque is limited to less than the requested torque, acombination of spark and motor torque may be used. The torque commandfor motor 442 is expressed in Equation 1 as follows:τ_(mot) _(—) _(reg)=min(τ_(mot) _(—) _(avail) _(—) _(max), max(τ_(mot)_(—) _(avail) _(—) _(min), (τ_(desired) _(—) _(fast)−τ_(eng) _(—)_(base)))),  (1)where □_(mot) _(—) _(req) is requested motor torque 638, □_(mot) _(—)_(avail) _(—) _(min) is the minimum available motor torque 634,□_(desired) _(—) _(fast) is the arbitrated, desired torque from all fastrequesters 622, and □_(eng) _(—) _(base) is a feedback signal fromengine controller 444, represented by estimated base engine torque 620.To cover the event when motor 442 is used to temporarily increasetorque, requested motor torque 638 is also limited by the maximumavailability of motor 442, expressed as □_(mot) _(—) _(avail) _(—)_(max) 632. The corresponding command for engine 436 is expressed inequation 2 as follows:τ_(eng) _(—) _(req) _(—) _(fast)=τ_(desired) _(—) _(fast)−τ_(mot) _(—)_(req),  (2)where □_(eng) _(—) _(req) _(—) _(fast) is requested fast engine torque246 achieved with spark timing control. Under this definition, enginecontroller 444 commands fast actuators such as spark timing and fuel tomeet requested fast engine torque 246.

Another scenario that can benefit from the present invention is tractioncontrol torque reduction. Similar to shift quality function, tractioncontrol requires a fast torque response. However, this response can be amore prolonged event depending upon the road surface. The presentinvention applies for limiting both base and fast torque requests whiletraction is compromised. In this case, motor torque provides thetransient difference between the actual and the requested base enginetorque.

Referring now to FIG. 10, a block diagram illustrating arbitration amongbase requests at the wheel level according to an embodiment of thepresent invention is shown. A wheel level arbiter, shown generally by660, generates arbitrated, desired wheel force 662 and arbitrated forcewinner 664 indicating which base request was selected by wheel levelarbiter 660. Wheel level arbiter 660 accepts driver desired wheel force666 and cruise control desired wheel force 668. Driver desired wheelforce 666 is based on position of the accelerator pedal. Cruise controldesired wheel force 668 is requested to maintain vehicle 430 at aconstant speed or other set-point. Intermediate desired wheel force 670is the maximum of driver desired wheel force 666 and cruise controldesired wheel force 668. Arbitrated desired wheel force 662 is theminimum of intermediate desired wheel force 670 and vehicle speed wheelforce limit 672, which is based on vehicle speed limitation.

In addition to generating arbitrated demand 662, wheel level arbiter 660outputs arbitrated force winner 664 providing an indication as to thesource of arbitrated desired wheel force 662. Torque limit speed controlindicator 674 and driver force indicator 676 are integer valuesindicating speed limiting and driver force, respectively. Arbitratedforce winner 664 is set to torque limit speed control indicator 674either if driver desired wheel force 666 is not greater than cruisecontrol desired wheel force 668 or if vehicle speed wheel force limit672 is not greater than driver desired wheel force 666.

Referring now to FIG. 11, a block diagram illustrating arbitration atthe transmission input level according to an embodiment of the presentinvention is shown. A transmission input level arbiter, shown generallyby 690, generates arbitrated desired transmission input base torque 692,arbitrated desired transmission input fast torque 694 and arbitratedtorque winner 696. Transmission input level arbiter 690 accepts avariety of inputs. Arbitrated desired transmission input base torque 692and arbitrated desired transmission input fast torque 694 are translatedbased on the operation of transmission 440. Arbitrated force winner 664indicates the winner of arbitrated requests occurring at wheel level 56.Fast torque shift limit 702 from transmission controller 448 requeststorque limit during shift for better shift quality. Maximum base torquelimit 704 and maximum fast torque limit 706 from transmission controller448 are provided to protect against mechanical damage to transmission440.

Transmission input level arbitrator 690 generates torque limit signal708 as a binary control signal asserted when transmission input desiredbase torque 698 is greater than maximum base torque limit 704.Intermediate base torque request 710 is the minimum of transmissioninput desired base torque 698 and maximum base torque limit 704.Arbitrated desired transmission input base torque 692 is the maximum ofintermediate base torque request 710 and fast torque shift limit 702.First intermediate fast torque request 712 is the minimum oftransmission input desired fast torque 700 and maximum fast torque limit706. Second intermediate fast torque request 714 is the maximum of firstintermediate fast torque request 712 and fast torque shift limit 702.Arbitrated desired transmission input fast torque 694 is the minimum ofsecond intermediate fast torque request 714 and arbitrated desiredtransmission input base torque 692.

Arbitrated torque winner 696 provides an integer indicating the sourcewinning arbitration within transmission input level arbiter 690.Mechanical limit indicator 716 indicates limiting to protecttransmission 440 from excessive base torque. Shift torque reductionindicator 718 indicates limiting due to modulation requested bytransmission controller 448 during a shift event. Arbitrated torquewinner 696 is set to mechanical limit indicator 716 when torque limitsignal 708 is asserted. If this is not the case, arbitrated torquewinner 696 is set to shift torque reduction indicator 718 iftransmission input desired fast torque 700 is greater than maximum fasttorque limit 706. Otherwise, arbitrated force winner 664 is sent asarbitrated torque winner 696.

Referring now to FIG. 12, a block diagram illustrating multilevel torqueresolution according to an embodiment of the present invention is shown.Torque resolution may be performed at any number of levels. In thegeneralized representation shown, first level resolver 730 arbitratesand/or coordinates first level torque input requests 732 to producefirst level resolved torque requests 734. First level resolved torquerequests 734 are translated by first level translator 736 to producetranslated first level torque requests 738. Second level resolver 740arbitrates and/or coordinates translated first level torque requests 738and any second level torque input requests 742 to produce second levelresolved torque requests 744. Second level resolved torque requests 744are translated by second level translator 746 to produce translatedsecond level torque requests 748.

This process may be repeated to match the architecture of any drivetrain. Resolved (n-1)^(st) level torque requests 750 are translated by(n-1)^(st) translator 752 to produce translated (n-1)^(st) level torquerequests 754. An n^(th) level resolver 756 accepts translated (n-1)^(st)level torque requests and any n^(th) level torque input requests 758 toproduce n^(th) level resolved torque requests. At any level, torqueinput requests 732, 742, 758 may be generated by torque requestorsoperating on that level and/or from torque requests translated fromanother level.

Various multilevel systems are possible. For example, a planetary gearset can have a different level for each of the sun gear, the planet gearcarrier and the annulus rotations.

Another example is a three level system including a transmission inputlevel, a differential input level and a wheel level. An engine and/ormotor operates at the transmission input level. An electric motor iscoupled to the drive shaft at the differential input. One or moreadditional motors or other torque producing devices operate at the wheellevel.

While embodiments of the invention have been illustrated and described,it is not intended that these embodiments illustrate and describe allpossible forms of the invention. For example, the present invention maybe applied to nonautomotive systems. It should be understood that thewords used in the specification are words of description rather thanlimitation and that various changes may be made without departing fromthe spirit and scope of the invention.

1. A method for use in an automotive vehicle having an engine and atleast one motor, the method comprising: receiving an engine base torquelevel indicating slowly changing torque produced by the engine;receiving a request for fast desired torque; determining as a motortorque a difference between the fast desired torque and the engine basetorque level; determining as an engine fast torque a difference betweenthe request for fast desired torque and the motor torque; determining amotor torque request as the motor torque; and determining an enginetorque request as the engine fast torque.
 2. The method according toclaim 1 wherein determining the motor torque further comprises limitingthe difference by at least one motor torque availability limitation. 3.The method according to claim 1 wherein the engine torque request isdetermined as a base engine torque request if the base engine torquerequest is less than the engine fast torque.
 4. The method according toclaim 1 further comprising limiting the motor torque with at least onemotor slew rate limitation prior to determining the engine fast torque.5. The method according to claim 1 further comprising receiving anindicator as to a source of the request for fast desired torque.
 6. Themethod according to claim 5 further comprising: receiving a request forintended motor torque; and determining the motor torque request as therequest for intended motor torque if the source of the request for fastdesired torque does not match one of the at least one allowable fastdesired torque requesters.
 7. The method according to claim 5 furthercomprising determining the motor torque request as the motor torque onlyif the source of the request for fast desired torque matches one of atleast one allowable fast desired torque requesters.
 8. The methodaccording to claim 5 further comprising: receiving a base engine torquerequest; and determining the engine torque request as the base enginetorque request if the source of the request for fast desired torque doesnot match one of the at least one allowable fast desired torquerequesters.
 9. The method according to claim 5 wherein the at least oneallowable fast desired torque requesters comprises a traction controltorque request.
 10. The method according to claim 5 wherein the at leastone allowable fast desired torque requesters comprises a transmissiontorque modulation request.
 11. A vehicle comprising: an engine supplyingengine torque to drive the vehicle, the engine torque based on an enginetorque request; at least one motor supplying motor torque to drive thevehicle, the motor torque based on a motor torque request; a pluralityof torque requesting sources; and control logic in communication withthe engine, the at least one motor and the plurality of torquerequesting sources, the control logic operative to (a) receive an enginebase torque level indicating slowly changing torque produced by theengine, (b) receive a request for fast desired torque, (c) determine asa motor torque a difference between the fast desired torque and theengine base torque level, this difference limited by at least one motortorque availability limitation, (d) determine as an engine fast torque adifference between the request for fast desired torque and the motortorque, (e) determine as the motor torque request the motor torque, and(f) determine as the engine torque request the engine fast torque. 12.The vehicle according to claim 11 wherein the engine torque request isdetermined as a base engine torque request if the base engine torquerequest is less than the engine fast torque.
 13. The vehicle accordingto claim 11 wherein the control logic limits the motor torque with atleast one motor slew rate limitation prior to determining the fastengine torque.
 14. The vehicle according to claim 11 wherein the controllogic receives an indicator as to a source of the request for fastdesired torque.
 15. The vehicle according to claim 14 wherein thecontrol logic is further operative to determine as the motor torquerequest the motor torque if the source of the request for fast desiredtorque matches one of at least one allowable fast desired torquerequesters.
 16. The vehicle according to claim 14 wherein the controllogic is further operative to determine as the motor torque request therequest for intended motor torque if the source of the request for fastdesired torque does not match one of the at least one allowable fastdesired torque requesters.
 17. The vehicle according to claim 14 whereinthe control logic is further operative to: receive a base engine torquerequest; and determine as the engine torque request the base enginetorque request if the source of the request for fast desired torque doesnot match one of the at least one allowable fast desired torquerequesters.
 18. The vehicle according to claim 14 wherein the at leastone allowable fast desired torque requesters comprises a tractioncontrol torque request.
 19. The vehicle according to claim 14 whereinthe at least one allowable fast desired torque requesters comprises atransmission torque modulation request.
 20. A method for controlling amotor vehicle having a plurality of torque producing sources forpropelling the vehicle, the method comprising: receiving a base torquelevel indicating slowly changing torque produced by a first propellingtorque source; receiving a request for fast desired torque; determininga second propelling source torque request based on a difference betweenthe fast desired torque and the base torque level, this differencelimited by at least one second propelling torque source availabilitylimitation; determining a first propelling source torque request basedon a difference between the request for fast desired torque and thesecond propelling torque source request; and providing the firstpropelling source torque request and the second propelling torque sourcerequest to the plurality of torque producing sources, whereby the motorvehicle is controlled.